Thanks for all the great replies. I am like most, when I see good deals I pick up 3 or 4 and keep adding them to the mix, either that or when I turn the light off they breed in there. 
I think we all become very subjective when asked this question and I doubt any serious enthusiast of the AR series hasnāt pondered this question one or more times.
Subjectively for me only I like 12 mags per rifle and 7 per pistol. As a cop I carry 3 pistol mags, so I have an complete extra set plus one floating around the car somewhere, for each of several pistols! For me 22ās donāt count, 3 or 4 seems to work. I generally use no more than 6 AR mags at a time whether in a class or training at the range so 12 again gives me double what I āneedā. And then you throw in all the extras put up and it gets kind of crazy.
Iām not sure each individual can really be subjective about their own needs as far as mags, only wants. How often do you shoot? They do wear out but not as often as some seem to think. Does your spouse or children have a rifle that you feed? To try to be realistic isnāt much fun but if I were buying one time and hoping they would last as long as I lasted (Iām 46) I would say 24 mags would last me based on my amount of shooting and type of shooting I do. Thatās replacing as needed and still having enough for the impending zombie attack. 
They would probably outlaw possession of mags no matter when they were made if they do another ban.
I try to shoot for 6-7 mags per AR. I believe the typical loadout is 6+1 mags?
Iād guess 50 or so AR mags, enough that I can give one to a friend thatās mag short now and then. 30 cal mags, 10 per rifle, pistol mags 6 to 10 per gun.
If Iām deeper than that in crap I hope I have friends on the way.
Careful scientific study of long term storage and actual firefights indicates that the correct answer is 42.
If you disagree, you are simply asking the wrong question.
I canāt tell if youāre being serious or not. Whatās throwing me off is its 6 combat loads (not counting the loaded mag edit and load on vest), so if you are serious, Iām curious to learn more about itā¦
If not, jokes on meā¦
FTS is right, 42 is the answer. In fact, it is the answer to most questions about life, the universe, and everything.
The way you worded it clicked. Brain fart. Jokes on meā¦